This invention concerns an apparatus for liposuction. Liposuction is a type of cosmetic surgery whereby undesirable accumulations of body fat are removed by suction. Liposuction is becoming increasingly popular, and is seen by many as a way to remove quickly any undesirable body fat which may or may not be removed by the more traditional ways of diet and exercise.
The traditional liposuction techniques include the use of a cannula connected to an external source of suction. An incision is made in the area of the fat desired to be removed, the cannula is inserted into the area, and the suction is begun. The fat is then vacuumed out of the body. This procedure has its disadvantages, however, because the fat is relatively difficult to separate from the surrounding tissue. Such separation sometimes causes excessive bleeding. In addition, it is difficult to keep the operation going without stopping to clean out the cannula. Normally, the surgeon attempts to compensate for this problem by rapidly moving the cannula within the cavity, and even periodically withdrawing it to allow the fat to move through the cannula. A further problem is that the surgeon must be careful not to allow the suction to remove or injure any desirable tissues, such as muscle, blood vessels, skin, subcutaneous tissues, and the like. Therefore, the speed, safety and effectiveness of the aforementioned liposuction method leaves much to be desired, and a successful operation depends on the practitioner's exceptional skill.
It is also known to use ultrasonically vibrating and aspirating probes in the field of liposuction surgery, as described in U.S. Pat. No. 4,886,491 to the present inventors. The procedure is to introduce the vibrating probe into the area of material desired to be removed, and use the ultrasonic vibrations to physically melt the fatty tissue. The fatty tissue can be emulsified by ultrasound and aspirated through the probe, using irrigation as an adjunct. It is known that a particularly effective probe for ultrasonic liposuction is a hollow cylindrical probe with a bullet shaped tip on the distal end. The tip can be welded or otherwise affixed to the probe. Both probe and tip can be manufactured from a variety of acoustically conductive metals, including cold-rolled steel, titanium, and aluminum. In presently known devices, the probe and tip are manufactured from the same materials, or from very similar materials, to ensure effective propagation of the ultrasonic waves all the way to the tip of the probe. Propagation of the waves to the distal tip of the probe is desirable, because this causes the tip of the probe to be able to melt and emulsify fat, facilitating insertion of the probe into the fatty tissue.
In previously known liposuction techniques, before the use of ultrasound, considerable physical exertion was necessary to force the tip of the probe into the fatty tissue. This was time consuming and dangerous, and it required considerable strength on the part of the physician. The currently known ultrasonic liposuction probes are much more easily inserted into the fatty tissue, because the tip of the probe can melt the tissue in advance of the probe. This essentially melts a hole through the fatty tissue, rather than punching a hole by force. This is a much safer procedure, since it allows the physician to exercise more complete control over the advancement of the probe.
There is a disadvantage sometimes associated with an ultrasonic probe having an acoustically conductive tip, however. For instance, when the probe has been inserted into the fatty tissue near the skin or the peritoneum, resistance can be met. When resistance is met, the wattage at the tip increases, and it can increase to the point of damaging the skin or the peritoneum. During such manipulations, the heat generated at the tip of the probe may be in excess of the heat reasonably required for the melting of fat at the tip. In other words, if care is not exercised, the tip may be hotter than it needs to be, and the result can be burning of tissues, damage of muscles or blood vessels, and even penetration of membranes such as the skin or the peritoneum. Therefore, the bullet shaped tip of acoustically conductive material, while it can be very beneficial during penetration, can under certain circumstances also be detrimental.
It is an object of the present invention to provide an ultrasonic liposuction probe which does not suffer from the disadvantage of having a tip which becomes too hot for certain manipulations of the probe. It is a further object of the present invention to provide a probe which has tips which can be interchanged to facilitate different types of probe manipulations. It is a still further object of the present invention to provide an ultrasonic liposuction device which is easy to use and economical to manufacture.